The present invention relates to a change speed operating apparatus for a tractor which comprises an oil hydraulic stepless change speed device, a change speed pedal for operating the oil hydraulic stepless change speed device, a change speed operating mechanism for connecting the oil hydraulic stepless change speed device and the change speed pedal mechanically, a neutral return mechanism for urging the change speed operating mechanism to return to a neutral position, a speed setting mechanism adapted for preventing the change speed operating mechanism from returning to a neutral position thereof from a desired operated position and for releasing prevention of the returning to the neutral position.
Normally, the above-mentioned speed setting mechanism is precisely connected to the change speed operating mechanism via rods and other elements without occurring play with connecting portions of the rods and each of the mechanisms so as to surely transmit the amount of the speed setting operation to the change speed operating mechanism.
The above change speed operating mechanism aims at operating the tractor at a constant speed while working and also at solving a trouble that a driver has to keep stepping the change speed pedal. However, it sometimes needs to accelerate the tractor from a constant speed for a short time while working. For instance, such is the case that a working load increases due to hard soil while cultivating the soil by means of a plow. In this case, since the above speed setting mechanism is provided only with limitted functions of keeping the amount of a speed setting operation and releasing the set position thereof, the driver has to step the change speed pedal to accelerate to get a desired speed after releasing the set position of the speed setting mechanism and thereafter decreasing the speed, the drive has to reset the speed setting mechanism. Thus, it is necessary to take many and complex steps in operation. This further means that a spare time is necessary to reset the speed setting mechanism at the previously set speed after the acceleration.